Professor Robin Milner, one of the pioneers of computer science, passed away on March 20: http://www.timesonline.co.uk/tol/comment/obituaries/article7081867.ece.
He will be remembered, among many other achievements, as the inventor of pi-calculus, the theoretical foundation behind Ateji Parallel Extensions.
Though I never had a chance to actually meet him, he inspired my career all along, as a researcher and as an entrepreneur.